For that 40G, I would suggest to stay with
GBR.
Try setting up separate 5G/10G to accomodate new GBR, a Q/T.
GBR is lot easier to keep than BR. Just give them what they need. Trust me, very easy to keep and breeed these GBR are.
What part of Jersey are you in? If you are near NYC or in Queens from time to time, I can notify you when I see good and healthy batch of GBR are in Town.
Although some staffs at Fishtown in Bayside Queens are ill mannered/rude, I personally dont care Only if I can obtain healthy and even mated pairs. They usually bring them in large quantity on Sun night thus few days or even week later should be enough time for fish to settle at
LFS.
I have not seen this many GBR in one shipment at any other lfs in Queens.
You could call for shipment schedule or I can notify you if you are planning to come to Queens. LMK. I'll see what I can do.
I have recently picked out few mated pairs from there for my friends. I may drive staffs somewhat crazy since I know which fish I want, but If I am buying 10 -15 mated pairs in one shot, they better have patience.
Again, Discus is not the best choice for that size tank. If neons/cardinals are large enough, would make good tankmates provided tank is larger, IMHO.
Try local cichlid clubs if and when possible (cheaper and healthier. They will tell you how easy GBR are to keep and breed.
Good Luck!